118 lines
2.9 KiB
Go
118 lines
2.9 KiB
Go
package crypto
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import (
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"crypto/rand"
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"crypto/rsa"
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"crypto/x509"
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"encoding/pem"
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"io"
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"code.google.com/p/go.crypto/ssh"
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"github.com/square/go-jose"
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)
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const (
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RSA_BITS = 2048 // Default number of bits in an RSA key
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RSA_BITS_MIN = 768 // Minimum number of bits in an RSA key
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)
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// standard characters allowed in token string.
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var chars = []byte("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789")
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// default token length
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var length = 32
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// Rand generates a 32-bit random string.
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func Rand() string {
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b := make([]byte, length)
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r := make([]byte, length+(length/4)) // storage for random bytes.
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clen := byte(len(chars))
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maxrb := byte(256 - (256 % len(chars)))
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i := 0
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for {
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io.ReadFull(rand.Reader, r)
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for _, c := range r {
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if c >= maxrb {
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// Skip this number to avoid modulo bias.
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continue
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}
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b[i] = chars[c%clen]
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i++
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if i == length {
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return string(b)
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}
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}
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}
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}
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// helper function to generate an RSA Private Key.
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func GeneratePrivateKey() (*rsa.PrivateKey, error) {
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return rsa.GenerateKey(rand.Reader, RSA_BITS)
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}
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// helper function that marshalls an RSA Public Key to an SSH
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// .authorized_keys format
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func MarshalPublicKey(public *rsa.PublicKey) []byte {
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private, err := ssh.NewPublicKey(public)
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if err != nil {
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return []byte{}
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}
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return ssh.MarshalAuthorizedKey(private)
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}
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// helper function that marshalls an RSA Private Key to
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// a PEM encoded file.
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func MarshalPrivateKey(private *rsa.PrivateKey) []byte {
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marshaled := x509.MarshalPKCS1PrivateKey(private)
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encoded := pem.EncodeToMemory(&pem.Block{Type: "RSA PRIVATE KEY", Headers: nil, Bytes: marshaled})
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return encoded
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}
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// UnmarshalPrivateKey is a helper function that unmarshals a PEM
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// bytes to an RSA Private Key
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func UnmarshalPrivateKey(private []byte) *rsa.PrivateKey {
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decoded, _ := pem.Decode(private)
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parsed, err := x509.ParsePKCS1PrivateKey(decoded.Bytes)
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if err != nil {
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return nil
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}
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return parsed
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}
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// Encrypt encrypts a secret string.
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func Encrypt(in, privKey string) (string, error) {
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rsaPrivKey, err := decodePrivateKey(privKey)
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if err != nil {
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return "", err
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}
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return encrypt(in, &rsaPrivKey.PublicKey)
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}
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// decodePrivateKey is a helper function that unmarshals a PEM
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// bytes to an RSA Private Key
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func decodePrivateKey(privateKey string) (*rsa.PrivateKey, error) {
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derBlock, _ := pem.Decode([]byte(privateKey))
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return x509.ParsePKCS1PrivateKey(derBlock.Bytes)
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}
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// encrypt encrypts a plaintext variable using JOSE with
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// RSA_OAEP and A128GCM algorithms.
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func encrypt(text string, pubKey *rsa.PublicKey) (string, error) {
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var encrypted string
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var plaintext = []byte(text)
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// Creates a new encrypter using defaults
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encrypter, err := jose.NewEncrypter(jose.RSA_OAEP, jose.A128GCM, pubKey)
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if err != nil {
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return encrypted, err
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}
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// Encrypts the plaintext value and serializes
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// as a JOSE string.
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object, err := encrypter.Encrypt(plaintext)
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if err != nil {
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return encrypted, err
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}
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return object.CompactSerialize()
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}
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